MAX1157AEUI+ Maxim Integrated, MAX1157AEUI+ Datasheet - Page 10

• Manufacturer Part Number: MAX1157AEUI+
• Description: Analog to Digital Converters - ADC 14-Bit 135ksps 4.2V Precision ADC
• Manufacturer: Maxim Integrated

Specifications of MAX1157AEUI+

• Rohs: yes
• Number Of Channels: 1
• Architecture: SAR
• Conversion Rate: 135 KSPs
• Resolution: 14 bit
• Input Type: Single-Ended
• Snr: 85 dB
• Interface Type: Parallel
• Operating Supply Voltage: 4.75 V to 5.25 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: TSSOP-28
• Maximum Power Dissipation: 1026 mW
• Minimum Operating Temperature: - 40 C
• Number Of Converters: 1
• Voltage Reference: 4.096 V

In shutdown mode, the reference and reference buffer
shut down between conversions. Shutdown mode
reduces supply current to 0.5µA (typ) immediately after
the conversion. The next falling edge of CS with R/C
low causes the reference and buffer to wake up and
enter acquisition mode. To achieve 14-bit accuracy,
allow 12ms (C
internal reference to wake up.
The internal reference of the MAX1157/MAX1159/
MAX1175 is internally buffered to provide +4.096V out-
put at REF. Bypass REF to AGND and REFADJ to
AGND with 10µF and 0.1µF, respectively.
Sink or source current at REFADJ to make fine adjust-
ments to the internal reference. The input impedance of
REFADJ is nominally 5kΩ. Use the circuit of Figure 7 to
adjust the internal reference to ±1.5%.
14-Bit, 135ksps, Single-Supply ADCs with
Bipolar Analog Input Range
Figure 6. Selecting Shutdown Mode
Figure 7. MAX1157/MAX1159/MAX1175 Reference Adjust
Circuit
10
______________________________________________________________________________________
100kΩ
150kΩ
Internal and External Reference
REFADJ
+5V
68kΩ
= 0.1µF, C
0.1µF
REFADJ
EOC
REF
R/C
CS
MAX1157
MAX1159
MAX1175
Internal Reference
Shutdown Mode
= 10µF) for the
ACQUISITION
CONVERSION
An external reference can be placed at either the input
(REFADJ) or the output (REF) of the MAX1157/
MAX1159/MAX1175’s internal buffer amplifier. Using
the buffered REFADJ input makes buffering the external
reference unnecessary. The input impedance of
REFADJ is typically 5kΩ. The internal buffer output
must be bypassed at REF with a 10µF capacitor.
Connect REFADJ to AV
Directly drive REF using an external 3.8V to 4.2V refer-
ence. During conversion, the external reference must
be able to drive 100µA of DC load current and have an
output impedance of 10Ω or less.
For optimal performance, buffer the reference through
an op amp and bypass REF with a 10µF capacitor.
Consider the MAX1157/MAX1159/MAX1175’s equivalent
input noise (0.6LSB) when choosing a reference.
EOC flags the microprocessor when a conversion is
complete. The falling edge of EOC signals that the data
is valid and ready to be output to the bus. D0–D13 are
the parallel outputs of the MAX1157/MAX1159/
MAX1175. These three-state outputs allow for direct
connection to a microcontroller I/O bus. The outputs
remain high-impedance during acquisition and conver-
sion. Data is loaded onto the bus with the third falling
edge of CS with R/C high (after t
forces the output bus back to high impedance. The
MAX1157/MAX1159/MAX1175 then wait for the next
falling edge of CS to start the next conversion cycle
(see Figure 2).
DATA
OUT
Reading the Conversion Result
DD
to disable the internal buffer.
DO
External Reference
). Bringing CS high